/*
 * Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file distributed with this work for additional information regarding copyright ownership. The ASF licenses this file to You under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.
 */
package com.opensource.dbhelp.dbutils.wrappers;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.sql.ResultSet;

import com.opensource.dbhelp.dbutils.ProxyFactory;

/**
 * Wraps a <code>ResultSet</code> to trim strings returned by the <code>getString()</code> and <code>getObject()</code> methods.
 * <p>
 * Usage Example: This example shows how to decorate ResultSets so processing continues as normal but all Strings are trimmed before being returned from the <code>ResultSet</code>.
 * </p>
 *
 * <pre>
 * 
 * ResultSet rs = // somehow get a ResultSet;
 * 
 * // Substitute wrapped ResultSet with additional behavior for real ResultSet
 * rs = StringTrimmedResultSet.wrap(rs);
 * 
 * // Pass wrapped ResultSet to processor
 * List list = new BasicRowProcessor().toBeanList(rs);
 * </pre>
 */
public class StringTrimmedResultSet implements InvocationHandler {

	/**
	 * The factory to create proxies with.
	 */
	private static final ProxyFactory factory = ProxyFactory.instance();

	/**
	 * Wraps the <code>ResultSet</code> in an instance of this class. This is equivalent to:
	 * 
	 * <pre>
	 * ProxyFactory.instance().createResultSet(new StringTrimmedResultSet(rs));
	 * </pre>
	 *
	 * @param rs
	 *            The <code>ResultSet</code> to wrap.
	 * @return wrapped ResultSet
	 */
	public static ResultSet wrap(ResultSet rs) {
		return factory.createResultSet(new StringTrimmedResultSet(rs));
	}

	/**
	 * The wrapped result.
	 */
	private final ResultSet rs;

	/**
	 * Constructs a new instance of <code>StringTrimmedResultSet</code> to wrap the specified <code>ResultSet</code>.
	 * 
	 * @param rs
	 *            ResultSet to wrap
	 */
	public StringTrimmedResultSet(ResultSet rs) {
		super();
		this.rs = rs;
	}

	/**
	 * Intercept calls to the <code>getString()</code> and <code>getObject()</code> methods and trim any Strings before they're returned.
	 *
	 * @see java.lang.reflect.InvocationHandler#invoke(Object, java.lang.reflect.Method, Object[])
	 * @param proxy
	 *            Not used; all method calls go to the internal result set
	 * @param method
	 *            The method to invoke on the result set
	 * @param args
	 *            The arguments to pass to the result set
	 * @return string trimmed result
	 * @throws Throwable
	 *             error
	 */
	@Override
	public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {

		Object result = method.invoke(this.rs, args);

		if ((method.getName().equals("getObject") || method.getName().equals("getString")) && result instanceof String) {
			result = ((String) result).trim();
		}

		return result;
	}

}